1. Field of Invention
This invention relates to devices for separating materials having different specific gravities. More specifically, this invention relates to a device for separating coal from waste material by liquid separation.
2. Prior Art
It is an important element in the mining and processing of coal and other solid material that rock and other waste material be removed from the raw product. For example, a well known procedure to separate usable coal from waste in raw coal is to pass the raw coal through a separation tank containing a liquid media which supports material with a selected specific gravity. When a specific liquid medium is used, the raw coal tends to float on the surface of the tank and flows through the separation tank without sinking. Waste material generally sinks to the bottom of the tank where it is collected and removed.
Several patents disclose devices for the washing and separating of coal or other solid material. For example, U.S. Pat. No. 4,409,098, Burke, discloses an apparatus for separating coal from raw coal using a liquid bath. This patent discloses a device useful in the separation of coal from raw coal wherein the raw coal is introduced into a liquid medium flowing across a separation tank between two pairs of baffle plates. See FIG. 2. The heavier waste material falls to the bottom of the device and is removed from the tank by a paddle wheel system wherein the arms of the paddle wheel system run through the flow of the liquid medium and between the two pairs of baffle plates.
Other devices for either the removal of material by a separatory procedure or for the washing of ore itself are disclosed in several patents. For example, U.S. Pat. No. 242,035, Peirce, discloses a semi-cylindrical box which receives ore at one end. Blades on a shaft move the ore towards the end of the box while flowing water carries off lighter material through discharge openings. The heavier material is picked up by shovels which dump this material over the sides of the box.
U.S. Pat. No. 246,706, Barber, et al., discloses a rotating wheel ore washer having buckets which are pivoted loosely such that the buckets pick up material in the bottom of a tank. As each bucket descends into the tank during rotation of the wheel, it is moved into engagement with certain projections which are secured to the opposite side of the tank to permit the removal of waste material from the tank.
U.S. Pat. No. 648,262, Honecker, discloses a coal separator containing a rotating shovel assembly for the removal of slate from a coal wash. Water is forced up through perforations in the bottom of the device to cause the coal to flow into a chute while the slate on the bottom is conveyed by an inclined shelf to a trough where it is lifted from the water by rotating buckets which discharge slate through openings into a tray.
U.S. Pat. No. 986,581, Long, discloses a complicated drum mechanism for the separation of material. Wash water is continually introduced into the interior of the drum to wash the light, worthless material toward the bottom of the drum while the heavier valuable constituents adhere to the lining of the drum.
U.S. Pat. No. 3,019,900, LaGrost, discloses a washing table or vat having a weir over which floating material passes into a draining chute. The vat has a bucket lifting wheel mounted for rotation about a horizontal axis and positioned so that the lower part of its path of travel is through the vat. The wheel picks up zinc material in the bottom and causes the zinc material to be directed inwardly against an outer surface plate from which it falls into a discharge chute.
U.S. Pat. Nos. 2,825,459 and 2,825,460, Schuetz, disclose devices for the washing of coal which remove heavier material from the coal as it falls to the bottom of a tank by use of rakes which move back and forth within the device.
U.S. Pat. No. 2,899,058, Tromp, discloses a complex apparatus for separating granule material having different specific gravities. The apparatus is disclosed of a solid drum-like cylinder containing vertical walls projecting from the sides of the cylinder through which the material is directed and blades for the removal of heavier material which drops to the bottom of the apparatus.
U.S. Pat. No. 3,493,108 discloses a device useful to increase the concentration of asbestos ore. It uses an oscillating sweeper for the removal of material that falls to the bottom of the device. See FIG. 5.
These patents disclose a number of devices useful for the removal of waste from coal and other solid separation procedures. However, there are certain problems that have not been solved by the prior art. For example, it is imperative for the full and complete separation of the usable coal from the waste that the liquid medium be undisturbed as it flows from one side of the separator to the other. Interruption of this flow occurring during the removal of the waste from the apparatus causes a reduction in the efficiency of separation. Any portion of the apparatus which moves through the flow of the coal can cause the coal to fracture or be carried to the bottom of the apparatus and thus be removed with the waste material. In addition, the less contact of the moving parts of the apparatus with the material flowing through the separator, the less damage will occur to the system. Thus, although there are many useful devices disclosed in the prior art for separation of coal, there is still a need for an improved apparatus for separating lighter specific gravity material from material having heavier specific gravity.
Therefore it is an object of this invention to provide a device for the separation of material of lighter specific gravity from material of heavier specific gravity.
It is another object of this invention to provide a new and unique apparatus for the separation of material of different specific gravity using a liquid medium wherein said medium is not disturbed by that portion of the apparatus which removes the waste.
It is a still further object of the invention to provide an apparatus for the separation of material of different specific gravity using a liquid medium where the down time of the apparatus is reduced because of the reduction or elimination of interference with the flow of the material by that portion of the apparatus which removes the waste.
These and other objects and features of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description, drawings and claims. The description along with the accompanying drawings provide a selected example of construction of the device to illustrate the invention.